arch/tile/kernel/signal.c

   1 /*
   2  * Copyright (C) 1991, 1992  Linus Torvalds
   3  * Copyright 2010 Tilera Corporation. All Rights Reserved.
   4  *
   5  *   This program is free software; you can redistribute it and/or
   6  *   modify it under the terms of the GNU General Public License
   7  *   as published by the Free Software Foundation, version 2.
   8  *
   9  *   This program is distributed in the hope that it will be useful, but
  10  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  12  *   NON INFRINGEMENT.  See the GNU General Public License for
  13  *   more details.
  14  */
  15
  16 #include <linux/sched.h>
  17 #include <linux/mm.h>
  18 #include <linux/smp.h>
  19 #include <linux/kernel.h>
  20 #include <linux/signal.h>
  21 #include <linux/errno.h>
  22 #include <linux/wait.h>
  23 #include <linux/unistd.h>
  24 #include <linux/stddef.h>
  25 #include <linux/personality.h>
  26 #include <linux/suspend.h>
  27 #include <linux/ptrace.h>
  28 #include <linux/elf.h>
  29 #include <linux/compat.h>
  30 #include <linux/syscalls.h>
  31 #include <linux/uaccess.h>
  32 #include <asm/processor.h>
  33 #include <asm/ucontext.h>
  34 #include <asm/sigframe.h>
  35 #include <asm/syscalls.h>
  36 #include <asm/vdso.h>
  37 #include <arch/interrupts.h>
  38
  39 #define DEBUG_SIG 0
  40
  41 /*
  42  * Do a signal return; undo the signal stack.
  43  */
  44
  45 int restore_sigcontext(struct pt_regs *regs,
  46                        struct sigcontext __user *sc)
  47 {
  48         int err = 0;
  49         int i;
  50
  51         /* Always make any pending restarted system calls return -EINTR */
  52         current_thread_info()->restart_block.fn = do_no_restart_syscall;
  53
  54         /*
  55          * Enforce that sigcontext is like pt_regs, and doesn't mess
  56          * up our stack alignment rules.
  57          */
  58         BUILD_BUG_ON(sizeof(struct sigcontext) != sizeof(struct pt_regs));
  59         BUILD_BUG_ON(sizeof(struct sigcontext) % 8 != 0);
  60
  61         for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
  62                 err |= __get_user(regs->regs[i], &sc->gregs[i]);
  63
  64         /* Ensure that the PL is always set to USER_PL. */
  65         regs->ex1 = PL_ICS_EX1(USER_PL, EX1_ICS(regs->ex1));
  66
  67         regs->faultnum = INT_SWINT_1_SIGRETURN;
  68
  69         return err;
  70 }
  71
  72 void signal_fault(const char *type, struct pt_regs *regs,
  73                   void __user *frame, int sig)
  74 {
  75         trace_unhandled_signal(type, regs, (unsigned long)frame, SIGSEGV);
  76         force_sigsegv(sig, current);
  77 }
  78
  79 /* The assembly shim for this function arranges to ignore the return value. */
  80 SYSCALL_DEFINE0(rt_sigreturn)
  81 {
  82         struct pt_regs *regs = current_pt_regs();
  83         struct rt_sigframe __user *frame =
  84                 (struct rt_sigframe __user *)(regs->sp);
  85         sigset_t set;
  86
  87         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
  88                 goto badframe;
  89         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  90                 goto badframe;
  91
  92         set_current_blocked(&set);
  93
  94         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
  95                 goto badframe;
  96
  97         if (restore_altstack(&frame->uc.uc_stack))
  98                 goto badframe;
  99
 100         return 0;
 101
 102 badframe:
 103         signal_fault("bad sigreturn frame", regs, frame, 0);
 104         return 0;
 105 }
 106
 107 /*
 108  * Set up a signal frame.
 109  */
 110
 111 int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
 112 {
 113         int i, err = 0;
 114
 115         for (i = 0; i < sizeof(struct pt_regs)/sizeof(long); ++i)
 116                 err |= __put_user(regs->regs[i], &sc->gregs[i]);
 117
 118         return err;
 119 }
 120
 121 /*
 122  * Determine which stack to use..
 123  */
 124 static inline void __user *get_sigframe(struct k_sigaction *ka,
 125                                         struct pt_regs *regs,
 126                                         size_t frame_size)
 127 {
 128         unsigned long sp;
 129
 130         /* Default to using normal stack */
 131         sp = regs->sp;
 132
 133         /*
 134          * If we are on the alternate signal stack and would overflow
 135          * it, don't.  Return an always-bogus address instead so we
 136          * will die with SIGSEGV.
 137          */
 138         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 139                 return (void __user __force *)-1UL;
 140
 141         /* This is the X/Open sanctioned signal stack switching.  */
 142         if (ka->sa.sa_flags & SA_ONSTACK) {
 143                 if (sas_ss_flags(sp) == 0)
 144                         sp = current->sas_ss_sp + current->sas_ss_size;
 145         }
 146
 147         sp -= frame_size;
 148         /*
 149          * Align the stack pointer according to the TILE ABI,
 150          * i.e. so that on function entry (sp & 15) == 0.
 151          */
 152         sp &= -16UL;
 153         return (void __user *) sp;
 154 }
 155
 156 static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 157                            sigset_t *set, struct pt_regs *regs)
 158 {
 159         unsigned long restorer;
 160         struct rt_sigframe __user *frame;
 161         int err = 0;
 162         int usig;
 163
 164         frame = get_sigframe(ka, regs, sizeof(*frame));
 165
 166         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 167                 goto give_sigsegv;
 168
 169         usig = current_thread_info()->exec_domain
 170                 && current_thread_info()->exec_domain->signal_invmap
 171                 && sig < 32
 172                 ? current_thread_info()->exec_domain->signal_invmap[sig]
 173                 : sig;
 174
 175         /* Always write at least the signal number for the stack backtracer. */
 176         if (ka->sa.sa_flags & SA_SIGINFO) {
 177                 /* At sigreturn time, restore the callee-save registers too. */
 178                 err |= copy_siginfo_to_user(&frame->info, info);
 179                 regs->flags |= PT_FLAGS_RESTORE_REGS;
 180         } else {
 181                 err |= __put_user(info->si_signo, &frame->info.si_signo);
 182         }
 183
 184         /* Create the ucontext.  */
 185         err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
 186         err |= __put_user(0, &frame->uc.uc_flags);
 187         err |= __put_user(NULL, &frame->uc.uc_link);
 188         err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
 189         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 190         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 191         if (err)
 192                 goto give_sigsegv;
 193
 194         restorer = VDSO_SYM(&__vdso_rt_sigreturn);
 195         if (ka->sa.sa_flags & SA_RESTORER)
 196                 restorer = (unsigned long) ka->sa.sa_restorer;
 197
 198         /*
 199          * Set up registers for signal handler.
 200          * Registers that we don't modify keep the value they had from
 201          * user-space at the time we took the signal.
 202          * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
 203          * since some things rely on this (e.g. glibc's debug/segfault.c).
 204          */
 205         regs->pc = (unsigned long) ka->sa.sa_handler;
 206         regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
 207         regs->sp = (unsigned long) frame;
 208         regs->lr = restorer;
 209         regs->regs[0] = (unsigned long) usig;
 210         regs->regs[1] = (unsigned long) &frame->info;
 211         regs->regs[2] = (unsigned long) &frame->uc;
 212         regs->flags |= PT_FLAGS_CALLER_SAVES;
 213         return 0;
 214
 215 give_sigsegv:
 216         signal_fault("bad setup frame", regs, frame, sig);
 217         return -EFAULT;
 218 }
 219
 220 /*
 221  * OK, we're invoking a handler
 222  */
 223
 224 static void handle_signal(unsigned long sig, siginfo_t *info,
 225                          struct k_sigaction *ka,
 226                          struct pt_regs *regs)
 227 {
 228         sigset_t *oldset = sigmask_to_save();
 229         int ret;
 230
 231         /* Are we from a system call? */
 232         if (regs->faultnum == INT_SWINT_1) {
 233                 /* If so, check system call restarting.. */
 234                 switch (regs->regs[0]) {
 235                 case -ERESTART_RESTARTBLOCK:
 236                 case -ERESTARTNOHAND:
 237                         regs->regs[0] = -EINTR;
 238                         break;
 239
 240                 case -ERESTARTSYS:
 241                         if (!(ka->sa.sa_flags & SA_RESTART)) {
 242                                 regs->regs[0] = -EINTR;
 243                                 break;
 244                         }
 245                         /* fallthrough */
 246                 case -ERESTARTNOINTR:
 247                         /* Reload caller-saves to restore r0..r5 and r10. */
 248                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 249                         regs->regs[0] = regs->orig_r0;
 250                         regs->pc -= 8;
 251                 }
 252         }
 253
 254         /* Set up the stack frame */
 255 #ifdef CONFIG_COMPAT
 256         if (is_compat_task())
 257                 ret = compat_setup_rt_frame(sig, ka, info, oldset, regs);
 258         else
 259 #endif
 260                 ret = setup_rt_frame(sig, ka, info, oldset, regs);
 261         if (ret)
 262                 return;
 263         signal_delivered(sig, info, ka, regs,
 264                         test_thread_flag(TIF_SINGLESTEP));
 265 }
 266
 267 /*
 268  * Note that 'init' is a special process: it doesn't get signals it doesn't
 269  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 270  * mistake.
 271  */
 272 void do_signal(struct pt_regs *regs)
 273 {
 274         siginfo_t info;
 275         int signr;
 276         struct k_sigaction ka;
 277
 278         /*
 279          * i386 will check if we're coming from kernel mode and bail out
 280          * here.  In my experience this just turns weird crashes into
 281          * weird spin-hangs.  But if we find a case where this seems
 282          * helpful, we can reinstate the check on "!user_mode(regs)".
 283          */
 284
 285         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 286         if (signr > 0) {
 287                 /* Whee! Actually deliver the signal.  */
 288                 handle_signal(signr, &info, &ka, regs);
 289                 goto done;
 290         }
 291
 292         /* Did we come from a system call? */
 293         if (regs->faultnum == INT_SWINT_1) {
 294                 /* Restart the system call - no handlers present */
 295                 switch (regs->regs[0]) {
 296                 case -ERESTARTNOHAND:
 297                 case -ERESTARTSYS:
 298                 case -ERESTARTNOINTR:
 299                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 300                         regs->regs[0] = regs->orig_r0;
 301                         regs->pc -= 8;
 302                         break;
 303
 304                 case -ERESTART_RESTARTBLOCK:
 305                         regs->flags |= PT_FLAGS_CALLER_SAVES;
 306                         regs->regs[TREG_SYSCALL_NR] = __NR_restart_syscall;
 307                         regs->pc -= 8;
 308                         break;
 309                 }
 310         }
 311
 312         /* If there's no signal to deliver, just put the saved sigmask back. */
 313         restore_saved_sigmask();
 314
 315 done:
 316         /* Avoid double syscall restart if there are nested signals. */
 317         regs->faultnum = INT_SWINT_1_SIGRETURN;
 318 }
 319
 320 int show_unhandled_signals = 1;
 321
 322 static int __init crashinfo(char *str)
 323 {
 324         const char *word;
 325
 326         if (*str == '\0')
 327                 show_unhandled_signals = 2;
 328         else if (*str != '=' || kstrtoint(++str, 0, &show_unhandled_signals) != 0)
 329                 return 0;
 330
 331         switch (show_unhandled_signals) {
 332         case 0:
 333                 word = "No";
 334                 break;
 335         case 1:
 336                 word = "One-line";
 337                 break;
 338         default:
 339                 word = "Detailed";
 340                 break;
 341         }
 342         pr_info("%s crash reports will be generated on the console\n", word);
 343         return 1;
 344 }
 345 __setup("crashinfo", crashinfo);
 346
 347 static void dump_mem(void __user *address)
 348 {
 349         void __user *addr;
 350         enum { region_size = 256, bytes_per_line = 16 };
 351         int i, j, k;
 352         int found_readable_mem = 0;
 353
 354         pr_err("\n");
 355         if (!access_ok(VERIFY_READ, address, 1)) {
 356                 pr_err("Not dumping at address 0x%lx (kernel address)\n",
 357                        (unsigned long)address);
 358                 return;
 359         }
 360
 361         addr = (void __user *)
 362                 (((unsigned long)address & -bytes_per_line) - region_size/2);
 363         if (addr > address)
 364                 addr = NULL;
 365         for (i = 0; i < region_size;
 366              addr += bytes_per_line, i += bytes_per_line) {
 367                 unsigned char buf[bytes_per_line];
 368                 char line[100];
 369                 if (copy_from_user(buf, addr, bytes_per_line))
 370                         continue;
 371                 if (!found_readable_mem) {
 372                         pr_err("Dumping memory around address 0x%lx:\n",
 373                                (unsigned long)address);
 374                         found_readable_mem = 1;
 375                 }
 376                 j = sprintf(line, REGFMT":", (unsigned long)addr);
 377                 for (k = 0; k < bytes_per_line; ++k)
 378                         j += sprintf(&line[j], " %02x", buf[k]);
 379                 pr_err("%s\n", line);
 380         }
 381         if (!found_readable_mem)
 382                 pr_err("No readable memory around address 0x%lx\n",
 383                        (unsigned long)address);
 384 }
 385
 386 void trace_unhandled_signal(const char *type, struct pt_regs *regs,
 387                             unsigned long address, int sig)
 388 {
 389         struct task_struct *tsk = current;
 390
 391         if (show_unhandled_signals == 0)
 392                 return;
 393
 394         /* If the signal is handled, don't show it here. */
 395         if (!is_global_init(tsk)) {
 396                 void __user *handler =
 397                         tsk->sighand->action[sig-1].sa.sa_handler;
 398                 if (handler != SIG_IGN && handler != SIG_DFL)
 399                         return;
 400         }
 401
 402         /* Rate-limit the one-line output, not the detailed output. */
 403         if (show_unhandled_signals <= 1 && !printk_ratelimit())
 404                 return;
 405
 406         printk("%s%s[%d]: %s at %lx pc "REGFMT" signal %d",
 407                task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
 408                tsk->comm, task_pid_nr(tsk), type, address, regs->pc, sig);
 409
 410         print_vma_addr(KERN_CONT " in ", regs->pc);
 411
 412         printk(KERN_CONT "\n");
 413
 414         if (show_unhandled_signals > 1) {
 415                 switch (sig) {
 416                 case SIGILL:
 417                 case SIGFPE:
 418                 case SIGSEGV:
 419                 case SIGBUS:
 420                         pr_err("User crash: signal %d,"
 421                                " trap %ld, address 0x%lx\n",
 422                                sig, regs->faultnum, address);
 423                         show_regs(regs);
 424                         dump_mem((void __user *)address);
 425                         break;
 426                 default:
 427                         pr_err("User crash: signal %d, trap %ld\n",
 428                                sig, regs->faultnum);
 429                         break;
 430                 }
 431         }
 432 }